The invention described herein was made in the performance of official duties by an employee of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon.
The invention relates generally to fragmenting warheads, and more particularly to the control of the polar ejection angle of fragments dispersed by a fragmenting warhead.
Fragmenting warheads are used in a variety of military applications to deliver a distribution of high-velocity fragments to a target area. In terms of airborne warheads, FIG. 1 depicts the essential elements of an end initiated fragmenting warhead. Specifically, a fragmentable casing 10 having a longitudinal centerline axis 11 houses an explosive material 12. To detonate explosive material 12 and rupture casing 10 into fragments, an initiator or detonator 14 is placed in casing 10 at one end thereof. Upon initiation, a detonation wave commences at detonator 14 and propagates through explosive material 12 along the direction of the longitudinal axis 11 of casing 10. When the detonation wave reaches casing 101 a shock wave is transmitted to the casing which, in turn, causes casing 10 to expand. Expansion of casing 10 is further facilitated by the expanding detonation product gases. Casing 10 ruptures into fragments as such expansion continues. These fragments are ejected radially outward along xe2x80x9cpolar ejection anglesxe2x80x9d measured perpendicular to the external surface of casing 10 at the specific location of rupturing casing 10. The polar ejection angle xcex1 is governed by the detonation velocity (VD) of explosive material 12 and the radial velocity (VF) of the fragments. The polar ejection angle can be approximated by one-half of the Taylor angle whereby
xcex1=arcsin[VF/(2VD)].
This is depicted in FIG. 1 where dashed line 16 represents the perpendicular direction relative to the external surface of casing 102 at the point of a particular polar ejection angle measurement. For a typical warhead, the polar ejection angle for the end initiated fragmenting warhead just described is approximately 7 degrees. As is known in the art, variations in polar ejection angle occur near each end of the warhead due to the build-up of the detonation wave and discontinuities in end confinement of the explosive material.
The essential features of another type of airborne fragmenting warhead are illustrated in FIG. 2 where detonators 24 and 26 are located at the respective forward and aft ends of the warhead. Detonators 24 and 26 are initiated simultaneously. Upon initiation, detonation waves starting at detonators 24 and 26 propagate through explosive material 14 from either end of the warhead. In this example, the polar ejection angle for the vast majority of the fragments is approximately 0 degrees due to the meeting of the two detonation waves originating from each end.
Unfortunately, there are many instances where the fixed polar ejection angles of 0 degrees or 7 degrees (generated by the above-described fragmenting warheads) do not provide the needed flexibility for a particular mission. Further, since the polar ejection angles in these examples are fixed, the warhead""s ability to adjust to a changing or moving target scenario is non-existent or at least severely limited.
Accordingly, it is an object of the present invention to provide for polar ejection angle control of a fragmenting warhead.
Another object of the present invention is to provide the means for adjusting the polar ejection angle of a fragmenting warhead to account for changing target scenarios.
Still another object of the present invention is to provide polar ejection angles for a fragmenting warhead that can range from negative 7 degrees to positive 7 degrees in a controllable fashion.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, control of the polar ejection angle of fragments in a fragmenting warhead is provided. The warhead""s casing is filled with explosive material and has at least two detonators spaced apart from one another and coupled to the explosive material. The detonators function in a non-simultaneous fashion to produce corresponding detonation waves in the explosive material. The detonation waves interact to control a polar ejection angle of fragments formed when the warhead""s casing ruptures. The present invention includes provisions for selecting specified times of detonation for each of the detonators after the warhead is deployed.